Effect of High-Fructose Corn Syrup on Biofilm Cariogenicity and Caries

Objectives: High-fructose corn syrup (HFCS) is common in processed foods, but it has been considered less cariogenic than sucrose (S) because, unlike S, it is not a substrate for biofilm extracellular polysaccharides (EPS) production. Here we investigate the effect of both on dental biofilm cariogenicity and structure when these sugars are used alone or alternately.
Methods: S. mutans biofilms (n=3) were formed on enamel slabs, and treated 8 times/day (feast periods), for 3 days, with 0.9% NaCl (negative control) or 292 mM of glucose+fructose (GF) (active control), S, or HFCS, and maintained overnight in low-sugar media (famine periods). Culture media changed before and after feast periods were assessed for pH and calcium concentration. Mineral loss in enamel slabs was estimated by percent surface hardness loss (%SHL). ANOVA/Tukey test were used to compare groups (α=5%). To assess biofilm structures, 24-h-old S. mutans biofilms (n=2) were treated 4 times, every 2 h, with media containing 29.2 mM of GF, S, HFCS, or SxHFCS alternately. Confocal microscopy was used to visualize biofilm cells (live/dead stain) and EPS (Alexa-fluor 647 dextran-conjugate).
Results: At the first feast period, media pH drop was significantly lower in the S group (5.6±0.1) than in the GF (5.9±0.05) or HFCS (5.8±0.04) groups, but subsequently they did not differ from each other (pH<5.5). More calcium was released to culture media in the S group, but no difference in %SHL was observed among all sugar-treated groups. Biofilms cyclically exposed to SxHFCS produced an EPS-rich structure resembling the S-only biofilm.
Conclusions: S caused lower pH drops at early biofilm development, probably due to EPS/biofilm build-up. However, HFCS is readily fermentable, suggesting its interspersed use with S could be as cariogenic as S alone.